PRESIDENT'S ADDRESS. 59 



the Black sea, because the latter has an outlet. It was immensely 

 larger than either, but its full size is not known. Its deposits, 

 however, are now found to occupy large districts, at intervals from 

 Northern Mexico to the British Possessions, and from near the 

 meridian of Great Salt Lake to western Kansas and Nebraska. It 

 occupied the region which, in the immediately preceding period, 

 was occupied by the oceanic belt before referred to. This belt was 

 changed from an oceanic condition to that of an inland sea, by such 

 a rise of the sea bottom at both the northern and southern portions 

 of the belt as connected together the eastern and western conti 

 nental areas, and gave the inclosed sea its inland position upon the 

 great united continent. 



That the waters of this great inland sea were soon considerably 

 freshened, is shown by the fact that its deposits contain no remains 

 of true marine forms. That its waters were in part brackish, is 

 shown by the presence of the remains of a large variety of forms 

 similar to those which now inhabit brackish waters only, and that 

 they were in part fresh, is shown by the presence of fresh-water 

 forms. A commingling of brackish and fresh-water forms is some 

 times found in the strata of the Laramie group, but usually the two 

 kinds are found respectively in alternating layers. This last named 

 fact indicates that there were, from time to time, such oscillations 

 of the bottom of this sea and its surrounding shores, as shifted the 

 salt and fresh-water areas respectively, so that their deposits locally 

 alternated with each other. And yet sedimentation in the Lara 

 mie sea went on continuously from the time when it was a part of 

 the open ocean, and also continuously into parts of the fresh-water 

 lakes which succeeded it. 



That this great inland sea contained, at times, broad islands, and 

 extensive marshes covered with a luxuriant vegetation, is shown by 

 the abundant beds of lignite and other vegetable remains ; and that 

 its marshes were peopled by great dinosaurs and other reptiles, is 

 shown by their remains, which are now found in various portions of 

 the Laramie group. That many fresh-water streams emptied into 



